Reducing Fossil Energy Use On The Farm

Conventional agriculture production relies heavily on fossil fuels, particularly in its ability to provide energy at a low cost

However, the uncertain future of fossil fuel availability and prices point to need to explore energy efficiencies in other cropping systems. Most of the U.S. Corn Belt relies on a two-year rotation of corn and soybean with heavy inputs of fertilizer, herbicides and pesticides derived from fossil fuels to achieve high yields keep costs low.

Matt Liebman, Michael Cruse, and their colleagues at Iowa State University conducted a six-year study to compare energy use of a conventionally managed corn and soybean system with two low input cropping systems that use more diverse crops and manure applications, but also use less fertilizer and herbicides. The results were published in the May/June 2010 edition of Agronomy Journal, published by the American Society of Agronomy.

The two input systems consisted of a three-year rotation of corn-soybean/small grain/red clover and a four-year rotation of corn-soybean-small grain/alfalfa-alfalfa. Between 2003 and 2008, nitrogen fertilizer inputs in the 3-year rotation decreased 66% and decreased 78% in the 4-year rotation.